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djk #165896 07/07/07 09:10 AM
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I really can't see that much problem with BS546.

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They can sit half-in/half out if pulled on as they've no locks. Also, they can come loose if the cables are pulled.


True, IEC309s latch together, but just how much of a problem is this in a typical lighting rig? Once the cables are run connected they're not generally subject to the same sort of rigors as, say, building site connections.

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They are prone to breakage if they're abused or crushed.


The same could be said for BS1363, and they're allowed in commercial use. The Duraplug style BS546 connectors are generally quite rugged enough for stage lighting use.

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Does stage lighting have RCD protection?


Probably not unless it's a TT supply, but what does that have to do with the connector types?

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They cant be used in outdoor rigs.


True, but neither can many of the light fittings they're used with here. What's the problem with using BS4343/IEC309 where necessary and BS546 for other applications?

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They are legally required here now though. If you put anything else in you're in breech of health and safety regulations.


That strikes me as being completely over the top.

When I was involved with amateur theatre (quite a few years ago now) we used a mixture of 5 and 15A BS546. 5A was adequate for 1kW spots/floods and a bank of 5A outlets certainly use up much less space than a bank of a similar number of IEC309s.

I understand though that professional theatre applications have moved toward using 15A for all connections in recent years and are phasing out use of 5A. There are still plenty in service though.

djk #165914 07/07/07 03:42 PM
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djk Offline OP
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Paul,

The major issue here is down to health and safety requirements and insurance.

Basically, rigging on a stage, or in a studio is now considered an area with mechanical hazards. So, all the equipment must be fitted with a recognised and approved connector that can cope in such an environment.

BS546 is no longer legally recognised in the regs here, IS401:1986 or IS401/A:1986 (BS1363) is and S EN 60309:1999 are. As are the IEC standards for IEC connectors etc.

I don't know about the UK, but in Ireland there were an unusual number of fires and electrical accidents in theatre installations. The health and safety people and insurers cracked down on it.

One of the major problems was the use of the standard, brittle version of BS546 rather than the rubber tough plug. Using IS EN 60309:1999 / CEEform eliminated this problem completely.

To be perfectly honest, having worked with this stuff in reality. I find the CEEform plugs perfectly practical in rigging. They're robust, and can't be pulled out accidently. Accidental pulling on cables is not at all unusual in a studio environment and it can lead to lights going off etc.

They're also available in black, so they're pretty much invisible in rigging. And pre-wired bars are easily available with CeeForm outlets and inlets.

It really hasn't been much of a problem. Overall, most people seem to prefer them as they can take quite a lot of pulling around, banging, falling from heights, having heavy equipment hit them etc..

I would agree though, all of this ultra-safe stuff is going a little over the top. But some of these industries brought the spotlight, if you'll pardon the pun, upon themselves through a history of installations done on a shoe string, equipment that was worn out and sloppy wiring and electrical safety practices.

That being said, anywhere there's a professional sparks working all the time the standards are usually very high.


Last edited by djk; 07/07/07 03:45 PM.
djk #165933 07/08/07 06:51 AM
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So what happens if a British/Northern Irish outfit travels down to the Republic? Presumably they are banned from using their BS546 extensions and panels?

There's an electrical section on this forum, in which different aspects of theatre connections often arise:

http://www.blue-room.org.uk


Hmmm.... I haven't checked that site for a while. There used to be a power/electrical section, but it seems to have disappeared for some reason.

Last edited by pauluk; 07/08/07 06:59 AM. Reason: Added last para.
djk #165974 07/09/07 06:53 AM
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Besides... did BS546 plugs ever have sheathed pins? If not I can see why they've been outlawed for stage use.

I only worked with smallish stage equipment here, that's connected with Schuko plugs/IEC to Schuko cords and usually fed from a nearby 16A CEE socket.

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Originally Posted by Texas_Ranger
Besides... did BS546 plugs ever have sheathed pins?


Not originally, but they've been available for the last few years. The commonly used (in the theatre) Duraplug (MK) doesn't have sheathed pins though.

To be honest, I think this sleeved-pin issue is something else which is being blown out of proportion as well, especially when one considers the possibility of much easier contact on something like a lampholder. You have an opening almost an inch wide with live pins easily accessible to even large fingers.

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I don't know... personally I think the risk of accidentally touching partially inserted plug pins is much greater than reaching into a lamp holder. I still have lots of old ungrounded round face plugs and caught myself several times very close to touching the live pins (mostly when I get lazy and try to plug in/unplug stuff single handed).
Especially when sockets are fairly tight you have to use force and get used to pressing one or more fingers against the cae plate and pull out the plug with the others... and that can get you pretty close to live metal!

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I have some pretty early BS546 plugs that did have sleeved pins - a red sleeve on the live and black on the neutral. I think they were made by GEC sometime in the 1940s or 1950s, I also have a Crabtree one with sleeving too, from around the same time. Obviously they were ahead of their time and didn't catch on, possibly due to the small extra cost. I'll see if I can get some pictures and have them posted.

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Come to think of it, I believe I've seen some old BS546 plugs like that too. Pretty rare though.

Going back to D.C. wire identification, are any of our Stateside members following this thread?

What would you use for 3-wire D.C. systems? The N.E.C. would require white or gray for the grounded middle wire, so with 3+Gnd. Romex presumably you'd then use red for positive, black for negative. But what about conduit wiring? The same, or maybe blue for negative?

What if a 120/208V system in the same building was already using black/red/blue/ white?

Last edited by pauluk; 07/10/07 12:41 PM. Reason: Typo.
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djk Offline OP
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Paul,
I still see new MK BS546 plugs without line pin sheaths. What's the deal there ? Is it actually in the BS546 revised spec or not?

Seems we're supposed to cut off / replace any older BS1363 plugs that don't have sheathed pins. Quite a rarity at this stage, hardly ever see them anymore, even on older appliances they seem to have been changed.

Last edited by djk; 07/12/07 06:53 AM.
djk #166080 07/12/07 09:10 AM
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Originally Posted by djk
Is it actually in the BS546 revised spec or not?


I'm not certain, but I don't think so. I have to confess that I don't follow all these standards revisions that closely, but as these plugs are still listed in catalogs as "BS546:1950" I would suspect that BS546 has never actually seen any revisions since 1950.

The standard MK BS546 5A (and 15A) plugs have hardly changed in decades. Old plug on the left, a new one purchased within the last year or so on the right:

[Linked Image]

[Linked Image]

The old plug bears the catalog no. MK1025 inside, the new one is MK1025A. Other than minor variations in the plating and the cord grip material, you can see that they're almost identical.

Both are marked "5A BSS546" on the base. The only other marking differences are that the new plug has "250V" stamped under the earth pin and the old one doesn't; the new plug has the earth symbol as well as "E" against the earth terminal inside; and the old plug says "Made in England" on the base whereas the new one just has a bar there and no indication of country of manufacture.

A rummage through my box has also revealed MK plugs which must be from somewhere in between these two: The "250V" and earth symbol markings are present, but they still say "Made in England."

Quote
Seems we're supposed to cut off / replace any older BS1363 plugs that don't have sheathed pins.


What, for all appliances no matter what? That's come into force here for businesses selling second-hand appliances here, although you'll still find older plugs in shops which haven't yet had the "pleasure" of a Trading Standards raid.

To be honest, when it comes to BS1363 I'd rather have a well made 40-year-old MK plug without sheathed pins than one of the cheap-and-nasty modern versions with them.

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